Description of problem: When documenting fast forward upgrade, an specific section for NFV needs to be created. It needs to include several steps: - explain minor update, specially focusing on ovs minor update from 2.6 to 2.9. It will also focus on how to perform vm migration, rebooting nodes without outage, etc - explain about how to do fast forward upgrade in batches: first ffu on undercloud, then on controllers, computes and ceph. Section by section will be explained, and the specific limitations of each step needs to be documented - explain about any config change in templates: for example, the changes needed in os-net-config after ffu. An initial reference document can be seen here: https://docs.google.com/document/d/1F3WSjXAqftorryEWr25bu5j4UHFW8ggia5LRVMCFkMs/edit
Slides for osp 10 minor update: https://docs.google.com/presentation/d/13-Itt16MdYQHKIxosk8fz8UjPnfONX2D0O4VgaHbmVA/edit#slide=id.g33021960a4_0_0